Leptin response to glucocorticoid occurs at physiological doses and is abolished by fasting

To examine the effects of graded doses of hydrocortisone (HC) on leptin secretion, and determine the effect of fasting.

This was a randomized, placebo-controlled, crossover study, with a 1-week "washout" period between interventions. Eight healthy subjects [age = 36 +/- 2.3 years (+/-SE), body mass index = 31.5 +/- 1.6 kg/m(2)] completed the dose-response study in which an intravenous infusion of saline (placebo) or HC (30 or 100 mg) was administered for 24 hours. Four healthy subjects (age = 35.2 +/- 3.0 years, body mass index = 27.1 +/- 2.1 kg/m(2)) completed the fasting study, which entailed continuous infusion of saline, HC (300 mg/24 hours) in the fed state, or HC (300 mg/24 hours) with total caloric deprivation for 24 hours. Blood sampling was performed every 1 to 2 hours for measurement of leptin, cortisol, insulin, and glucose levels.

Peak hyperleptinemia occurred after 16 hours of HC infusion; peak/baseline leptin levels were 129% (placebo), 140% (30 mg of HC for 24 hours, p = 0.05), and 185% (100 mg of HC for 24 hours, p < 0.01). During infusion of HC (300 mg/24 hours or placebo), the peak/baseline plasma leptin levels were 16.1 +/- 5.8/12.8 +/- 5.9 ng/mL (placebo with food, 126%), 14.6 +/- 6.0/12.5 +/- 6.5 ng/mL (HC fasting, 117%), and 32.5 +/- 12.5/12.0 +/- 8.4 ng/mL (HC with food, 271%, p < 0.001).

Leptin secretory responses occur at physiological doses of HC, are obliterated by fasting, and thus may be of metabolic significance.